Cherry pick d2d40ea8cf13d474b3fb64f946006b3b539c115e from atomiclama

Squashed commit of the following:
commit ba4ef96
Author: atomiclama <atomiclama@somewhere.com>
Date:   Mon Oct 3 10:45:24 2016 +0100

rebased

commit b8780a6
Author: atomiclama <atomiclama@somewhere.com>
Date:   Mon Oct 3 10:19:07 2016 +0100

comment added

commit 2a7144c
Author: atomiclama <atomiclama@somewhere.com>
Date:   Fri Sep 30 16:21:07 2016 +0100

fixed interframe value of 500us for both protocols.
Setup variables on first occurance of correct sync byte.

commit 4c3a503
Author: atomiclama <atomiclama@somewhere.com>
Date:   Fri Sep 30 13:09:20 2016 +0100

First working point for autodetect

commit d947e5d
Author: atomiclama <atomiclama@somewhere.com>
Date:   Wed Sep 28 09:20:58 2016 +0100

Merge remote-tracking branch 'androck/development' into
vtx-betaflight-dev

Reworked so that it's based on serial provider instead of the extra
config entry.
This saves space but requires a change in the configurator.

src/main/config/config.c

@@ -523,7 +523,6 @@ void createDefaultConfig(master_t *config)
 #else
     config->rxConfig.serialrx_provider = 0;
 #endif
-    config->rxConfig.ibus_model = 0;
     config->rxConfig.sbus_inversion = 1;
     config->rxConfig.spektrum_sat_bind = 0;
     config->rxConfig.spektrum_sat_bind_autoreset = 1;

src/main/io/serial_cli.c

@@ -429,10 +429,6 @@ static const char * const lookupTableSerialRX[] = {
 };
 #endif
 
-static const char * const lookupTableIbusModel[] = {
-    "IA6B", "IA6"
-};
-
 static const char * const lookupTableGyroLpf[] = {
     "OFF",
     "188HZ",
@@ -550,7 +546,6 @@ typedef enum {
 #ifdef SERIAL_RX
     TABLE_SERIAL_RX,
 #endif
-    TABLE_IBUS_MODEL,
     TABLE_GYRO_LPF,
     TABLE_ACC_HARDWARE,
 #ifdef BARO
@@ -590,7 +585,6 @@ static const lookupTableEntry_t lookupTables[] = {
 #ifdef SERIAL_RX
     { lookupTableSerialRX, sizeof(lookupTableSerialRX) / sizeof(char *) },
 #endif
-    { lookupTableIbusModel, sizeof(lookupTableIbusModel) / sizeof(char *) },
     { lookupTableGyroLpf, sizeof(lookupTableGyroLpf) / sizeof(char *) },
     { lookupTableAccHardware, sizeof(lookupTableAccHardware) / sizeof(char *) },
 #ifdef BARO
@@ -736,7 +730,6 @@ const clivalue_t valueTable[] = {
 #ifdef SERIAL_RX
     { "serialrx_provider",          VAR_UINT8  | MASTER_VALUE | MODE_LOOKUP,  &masterConfig.rxConfig.serialrx_provider, .config.lookup = { TABLE_SERIAL_RX } },
 #endif
-    { "ibus_model",                 VAR_UINT8  | MASTER_VALUE | MODE_LOOKUP,  &masterConfig.rxConfig.ibus_model, .config.lookup = { TABLE_IBUS_MODEL } },
     { "sbus_inversion",             VAR_UINT8  | MASTER_VALUE | MODE_LOOKUP,  &masterConfig.rxConfig.sbus_inversion, .config.lookup = { TABLE_OFF_ON } },
 #ifdef SPEKTRUM_BIND
     { "spektrum_sat_bind",          VAR_UINT8  | MASTER_VALUE,  &masterConfig.rxConfig.spektrum_sat_bind, .config.minmax = { SPEKTRUM_SAT_BIND_DISABLED,  SPEKTRUM_SAT_BIND_MAX} },

src/main/rx/ibus.c

@@ -46,15 +46,15 @@
 #define IBUS_BUFFSIZE 32
 #define IBUS_MODEL_IA6B 0
 #define IBUS_MODEL_IA6 1
+#define IBUS_FRAME_GAP 500
 
 #define IBUS_BAUDRATE 115200
 
-static uint8_t ibusModel = 0;
+static uint8_t ibusModel;
-static uint8_t ibusSyncByte = 0x20;
+static uint8_t ibusSyncByte;
-static uint8_t ibusFrameSize = 32;
+static uint8_t ibusFrameSize;
-static uint8_t ibusChannelOffset = 2;
+static uint8_t ibusChannelOffset;
-static uint32_t ibusInterframeGap = 3000;
+static uint16_t ibusChecksum;
-static uint16_t ibusChecksum = 0xFFFF;
 
 static bool ibusFrameDone = false;
 static uint32_t ibusChannelData[IBUS_MAX_CHANNEL];
@@ -64,19 +64,13 @@ static uint16_t ibusReadRawRC(rxRuntimeConfig_t *rxRuntimeConfig, uint8_t chan);
 
 bool ibusInit(rxConfig_t *rxConfig, rxRuntimeConfig_t *rxRuntimeConfig, rcReadRawDataPtr *callback)
 {
-
+    UNUSED(rxConfig);
-    if (rxConfig->ibus_model == IBUS_MODEL_IA6) {
-        ibusModel = 1;
-        ibusSyncByte = 0x55;
-        ibusFrameSize = 31;
-        ibusInterframeGap = 500;
-        ibusChecksum = 0x0000;
-        ibusChannelOffset = 1;
-    }
 
     if (callback)
         *callback = ibusReadRawRC;
 
+    ibusSyncByte = 0;
+
     rxRuntimeConfig->channelCount = IBUS_MAX_CHANNEL;
 
     serialPortConfig_t *portConfig = findSerialPortConfig(FUNCTION_RX_SERIAL);
@@ -112,13 +106,32 @@ static void ibusDataReceive(uint16_t c)
 
     ibusTime = micros();
 
-    if ((ibusTime - ibusTimeLast) > ibusInterframeGap) 
+    if ((ibusTime - ibusTimeLast) > IBUS_FRAME_GAP)
         ibusFramePosition = 0;
 
     ibusTimeLast = ibusTime;
 
-    if (ibusFramePosition == 0 && c != ibusSyncByte)
+    if (ibusFramePosition == 0) {
-        return;
+        if (ibusSyncByte == 0) {
+            // detect the frame type based on the STX byte.
+            if (c == 0x55) {
+                ibusModel = IBUS_MODEL_IA6;
+                ibusSyncByte = 0x55;
+                ibusFrameSize = 31;
+                ibusChecksum = 0x0000;
+                ibusChannelOffset = 1;
+            } else if (c == 0x20) {
+                ibusModel = IBUS_MODEL_IA6B;
+                ibusSyncByte = 0x20;
+                ibusFrameSize = 32;
+                ibusChannelOffset = 2;
+                ibusChecksum = 0xFFFF;
+            } else
+                return;
+        } else if (ibusSyncByte != c) {
+            return;
+        }
+    }
 
     ibus[ibusFramePosition] = (uint8_t)c;
 
@@ -143,20 +156,19 @@ uint8_t ibusFrameStatus(void)
 
     chksum = ibusChecksum;
     rxsum = ibus[ibusFrameSize - 2] + (ibus[ibusFrameSize - 1] << 8);
-    
     if (ibusModel == IBUS_MODEL_IA6) {
-	    for (i = 0, offset = ibusChannelOffset; i < IBUS_MAX_CHANNEL; i++, offset += 2)
+        for (i = 0, offset = ibusChannelOffset; i < IBUS_MAX_CHANNEL; i++, offset += 2)
-		chksum += ibus[offset] + (ibus[offset + 1] << 8);
+            chksum += ibus[offset] + (ibus[offset + 1] << 8);
-    } else { 
+    } else {
-	    for (i = 0; i < 30; i++)
+        for (i = 0; i < 30; i++)
-		chksum -= ibus[i];
+            chksum -= ibus[i];
     }
 
     if (chksum == rxsum) {
         for (i = 0, offset = ibusChannelOffset; i < IBUS_MAX_CHANNEL; i++, offset += 2) {
-	    ibusChannelData[i] = ibus[offset] + (ibus[offset + 1] << 8);
+            ibusChannelData[i] = ibus[offset] + (ibus[offset + 1] << 8);
-	}
+        }
-	frameStatus = SERIAL_RX_FRAME_COMPLETE;
+        frameStatus = SERIAL_RX_FRAME_COMPLETE;
     }
 
     return frameStatus;

src/main/rx/rx.h

@@ -112,7 +112,6 @@ typedef struct rxChannelRangeConfiguration_s {
 typedef struct rxConfig_s {
     uint8_t rcmap[MAX_MAPPABLE_RX_INPUTS];  // mapping of radio channels to internal RPYTA+ order
     uint8_t serialrx_provider;              // type of UART-based receiver (0 = spek 10, 1 = spek 11, 2 = sbus). Must be enabled by FEATURE_RX_SERIAL first.
-    uint8_t ibus_model;
     uint8_t sbus_inversion;                 // default sbus (Futaba, FrSKY) is inverted. Support for uninverted OpenLRS (and modified FrSKY) receivers.
     uint8_t spektrum_sat_bind;              // number of bind pulses for Spektrum satellite receivers
     uint8_t spektrum_sat_bind_autoreset;    // whenever we will reset (exit) binding mode after hard reboot